1. Statement of the Technical Field
The inventive arrangements relate to directional couplers for dividing or splitting an input signal into multiple outputs, or combining multiple input signals into a single output.
2. Description of Related Art
Directional couplers are commonly used in various telecommunications-related applications such as power dividing and combining; combining feeds to and from antennas; antenna beam forming; phase shifting; etc. Commercially available directional couplers are usually categorized as either waveguide-based or thin-film-based. Typical waveguide-based couplers have relatively high power-handling capacity, but possess a relatively large dimensional footprint. Typical thin-film-based couplers have a relatively small dimensional footprint, but possess relatively low power-handling capacity.
The frequency response of directional couplers is usually fixed, e.g., the frequency (or frequency band) at which maximum power transfer will occur cannot be varied. Thus, the performance of such a coupler cannot be optimized or tuned for multiple operating conditions.
Three-dimensional microstructures can be formed by utilizing sequential build processes. For example, U.S. Pat. Nos. 7,012,489 and 7,898,356 describe methods for fabricating coaxial waveguide microstructures. These processes provide an alternative to traditional thinfilm technology, but also present new design challenges pertaining to their effective utilization for advantageous implementation of various devices such as miniaturized switches.